The list below shows the STEP Application Protocols (APs), which are all built on the same set of Integrate Resources (IRs) so they all use the same definitions for the same information. For example, AP203, AP214, AP238, and AP242 use the same definitions for three dimensional geometry, assembly data and basic product information.
Each AP has a scope that describes its purpose, an activity diagram describing the functions that an engineer needs to perform within that scope, and an Application Requirement Model describing the information requirements of those activities. These information requirements are then mapped into the common set of Integrated Resources and the result is a data exchange standard for the activities within the scope.
The ultimate goal is to cover the entire life cycle, from conceptual design to final disposal, for all kinds of products. However, the most tangible use of STEP today is the ability to exchange design data as solid models and assemblies of solid models.
STEP led the way with three dimensional data exchange by organizing an implementation forum for the CAD vendors so that they could continually improve the quality of the solid model data exchanges. The history of this success is relatively interesting because it show that the initial reluctance of vendors to implement user-defined standards can be overcome with enough perseverance.
At first, in 1996, there was a significant body of opinion that solid model geometry data could not be exchanged between systems using a neutral standard. However, in 1997 Ford, Allied Signal and STEP Tools, Inc. demonstrated the first successful data exchange of 3D geometry using STEP. Once this basic capability had been demonstrated a pilot project, called AeroSTEP, was organized by Boeing and its Aircraft engine vendors to test the first translators by exchanging data about where an engine fits onto the airframe. This project started out by exchanging simple faceted models but eventually demonstrated the exchange of models with great complexity.
The AeroSTEP project made it clear that STEP data exchange of solid model data was both feasible and valuable. As a result, vendor neutral implementation forums were formed in Europe, the Far East and the USA and the quality of the translators was raised to the level that allowed anyone, including ordinary users in small organizations, to use STEP for data exchange of solid models after about 2001.